This invention relates to motion monitors, and, in particular, to motion monitors used to measure the motion that one structural member experiences relative to another structural member.
For a variety of reasons, including both settlement and faulty construction materials, structures such as old or new buildings often develop cracks or faults in its structural members such as concrete walls or foundations. The portions of the structural members on opposite sides of the cracks experience shifting relative to one another. Besides breaking and shifting along cracks, a structural member may also shift or move relative to adjacent structural members along joint intersections therebetween. In order to monitor the size and motion of these joints and cracks to, for example, better predict potential damaging failure, various devices have been developed. For instance, electronic measurement devices have been employed. Overlaying grids have also been used in fault monitoring and measuring. In addition to potentially being expensive, these types of devices may also suffer from another shortcoming. In particular, while useful to determine at a given inspection time the relative positions of crack or joint separated structural members in comparison to a known control position, these devices do not indicate to an inspector how or along what path the crack separated structural member portions shifted in the process of the structural member portions achieving their present inspected positions.
Another application for motion monitoring devices affects construction or building related fields and relates to vibratory motion. Because the extent or intensity of cyclic, vibratory movement of one structural member relative to another structural member may, for example, implicate material fatigue concerns, proficient measurement of these movements is desirable to be achieved.